linux-kernel - Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved

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Message-ID: <9d688cd8-99e3-0265-06aa-d44597e7686c@omp.ru>
Date:   Fri, 10 Dec 2021 22:01:04 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sergei Shtylyov <sergei.shtylyov@...il.com>
CC:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        <linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when
 IRQ can't be retrieved

On 12/10/21 8:59 PM, Andy Shevchenko wrote:

>>>>>>>> platform_get_irq() will print a message when it fails.
>>>>>>>> No need to repeat this.
>>>>>>>>
>>>>>>>> While at it, drop redundant check for 0 as platform_get_irq() spills
>>>>>>>> out a big WARN() in such case.
>>>>>>>
>>>>>>> The reason you should be able to remove the "if (!irq)" test is that
>>>>>>> platform_get_irq() never returns 0. At least, that is what the function kdoc
>>>>>>> says. But looking at platform_get_irq_optional(), which is called by
>>>>>>> platform_get_irq(), the out label is:
>>>>>>>
>>>>>>> 	WARN(ret == 0, "0 is an invalid IRQ number\n");
>>>>>>> 	return ret;
>>>>>>>
>>>>>>> So 0 will be returned as-is. That is rather weird. That should be fixed to
>>>>>>> return -ENXIO:
>>>>>>>
>>>>>>> 	if (WARN(ret == 0, "0 is an invalid IRQ number\n"))
>>>>>>> 		return -ENXIO;
>>>>>>> 	return ret;
>>>>>>
>>>>>>    My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this
>>>>>> but returns -EINVAL instead.
>>>>>>
>>>>>>> Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ?
>>>>>>
>>>>>>    Of course it isn't...
>>>>>
>>>>> It's unsubstantiated statement. The vIRQ 0 shouldn't be returned by any of
>>>>> those API calls.
>>>>
>>>>    We do _not_ know what needs to be fixed, that's the problem, and that's why the WARN()
>>>> is there...
>>>
>>> So, have you seen this warning (being reported) related to libahci_platform?
>>
>>    No (as if you need to really see this while it's obvious from the code review).
>>
>>> If no, what we are discussing about then? The workaround is redundant and
>>
>>    I don't know. :-) Your arguments so far seem bogus (sorry! :-))...
> 
> It seems you haven't got them at all. The problems of platform_get_irq() et al
> shouldn't be worked around in the callers.

   I have clearly explained to you what I'm working around there. If that wasn't clear
enough, I don't want to continue this talk anymore. Good luck with your patch (not this
one).

[...]

MBR, Sergey